Heat shield, systems and methods

ABSTRACT

A heat shield may include a base portion, wherein the base portion bounds a triangular void, a top portion, wherein the top portion bounds an ovular void, and a tapered portion, wherein the tapered portion extends between the base portion and the top portion, the top portion having a smaller cross-sectional area than the base portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, and claims priority to, and thebenefit of U.S. patent application Ser. No. 14/682,767, filed on Apr. 9,2015, and entitled “HEAT SHIELD, SYSTEMS AND METHODS” which isincorporated by reference herein in its entirety.

FIELD

This disclosure relates to a gas turbine engine, and more particularlyto heat shields for oil tube fittings.

BACKGROUND

Engine oil tubes and fittings may be subjected to relatively hightemperatures. Once subjected to excessive heating, oil may undergocoking. Oil coking may cause solid oil deposits to form within oiltubes, causing undesirable effects such as blocked passageways andfilters.

SUMMARY

A heat shield is described herein, in accordance with variousembodiments. A heat shield may comprise a base portion, a top portion,and a tapered portion extending between the top portion and the bottomportion. The base portion may comprise a sheet metal bounding atriangular void. The top portion may comprise a sheet metal bounding anovular void.

A lubricating assembly is described herein, in accordance with variousembodiments. A lubricating assembly may include an oil tube, a fitting,and a heat shield. The fitting may be configured to be attached to theoil tube. The heat shield may be configured to be attached to the oiltube. In various embodiments, the oil tube may be dual wall oil tubecomprising an inner wall and an outer wall.

A method of cooling an oil tube fitting is disclosed herein, inaccordance with various embodiments. The method of cooling an oil tubefitting may include disposing a heat shield about an oil tube. When inthe installed position, the heat shield may at least partially encase anoil tube fitting. When in the installed position and during operation,the heat shield may be configured to prevent heat transfer between theoil tube fitting and surrounding hot air. When in the installedposition, the heat shield may be configured to be separated from the oiltube fitting by a gap.

Introducing a heat shield may prevent oil tube fittings from excessivelyheating, preventing oil coking.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example gas turbine engine, in accordance withvarious embodiments;

FIG. 2A illustrates a schematic view of an example mid-turbine frameassembly, in accordance with various embodiments;

FIG. 2B illustrates a schematic view of an oil tube fitting heat shieldassembly, in accordance with various embodiments;

FIG. 3A illustrates a side view of an oil tube fittings heat shieldassembly, in accordance with various embodiments; and

FIG. 3B illustrates a top view of an oil tube fitting heat shield, inaccordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration. While these exemplary embodiments are described insufficient detail to enable those skilled in the art to practice theinventions, it should be understood that other embodiments may berealized and that logical changes and adaptations in design andconstruction may be made in accordance with this invention and theteachings herein. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation. The scope of theinvention is defined by the appended claims. For example, the stepsrecited in any of the method or process descriptions may be executed inany order and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact. Surface shading lines may be used throughout thefigures to denote different parts but not necessarily to denote the sameor different materials. In some cases, reference coordinates may bespecific to each figure.

As used herein, “aft” refers to the direction associated with the tail(e.g., the back end) of an aircraft, or generally, to the direction ofexhaust of the gas turbine. As used herein, “forward” refers to thedirection associated with the nose (e.g., the front end) of an aircraft,or generally, to the direction of flight or motion.

As used herein, “distal” refers to the direction radially outward, orgenerally, away from the axis of rotation of a turbine engine. As usedherein, “proximal” refers to a direction radially inward, or generally,towards the axis of rotation of a turbine engine.

In various embodiments and with reference to FIG. 1, a gas turbineengine 20 is provided. Gas turbine engine 20 may be a two-spool turbofanthat generally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mayinclude, for example, an augmenter section among other systems orfeatures. In operation, fan section 22 can drive air along a bypassflow-path B while compressor section 24 can drive air for compressionand communication into combustor section 26 then expansion throughturbine section 28. Although depicted as a turbofan gas turbine engine20 herein, it should be understood that the concepts described hereinare not limited to use with turbofans as the teachings may be applied toother types of gas turbine engines including three-spool architectures.

Gas turbine engine 20 may generally comprise a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A-A′ relative to an engine static structure 36 via oneor more bearing systems 38 (shown as bearing system 38-1 and bearingsystem 38-2). It should be understood that various bearing systems 38 atvarious locations may alternatively or additionally be provided,including for example, bearing system 38, bearing system 38-1, andbearing system 38-2.

Low speed spool 30 may generally comprise an inner shaft 40 thatinterconnects a fan 42, a low pressure (or first) compressor section 44(also referred to a low pressure compressor) and a low pressure (orfirst) turbine section 46. Inner shaft 40 may be connected to fan 42through a geared architecture 48 that can drive fan 42 at a lower speedthan low speed spool 30. Geared architecture 48 may comprise a gearassembly 60 enclosed within a gear housing 62. Gear assembly 60 couplesinner shaft 40 to a rotating fan structure. High speed spool 32 maycomprise an outer shaft 50 that interconnects a high pressure compressor52 (e.g., a second compressor section) and high pressure (or second)turbine section (“HPT”) 54. A combustor 56 may be located between highpressure compressor 52 and HPT 54. A mid-turbine frame 57 of enginestatic structure 36 may be located generally between HPT 54 and lowpressure turbine 46. Mid-turbine frame 57 may support one or morebearing systems 38 in turbine section 28. Inner shaft 40 and outer shaft50 may be concentric and rotate via bearing systems 38 about the enginecentral longitudinal axis A-A′, which is collinear with theirlongitudinal axes. As used herein, a “high pressure” compressor orturbine experiences a higher pressure than a corresponding “lowpressure” compressor or turbine.

The core airflow may be compressed by low pressure compressor 44 thenhigh pressure compressor 52, mixed and burned with fuel in combustor 56,then expanded over HPT 54 and low pressure turbine 46. Mid-turbine frame57 includes airfoils 59 which are in the core airflow path. Low pressureturbine 46 and HPT 54 rotationally drive the respective low speed spool30 and high speed spool 32 in response to the expansion.

Gas turbine engine 20 may be, for example, a high-bypass geared aircraftengine. In various embodiments, the bypass ratio of gas turbine engine20 may be greater than about six (6). In various embodiments, the bypassratio of gas turbine engine 20 may be greater than ten (10). In variousembodiments, geared architecture 48 may be an epicyclic gear train, suchas a star gear system (sun gear in meshing engagement with a pluralityof star gears supported by a carrier and in meshing engagement with aring gear) or other gear system. Geared architecture 48 may have a gearreduction ratio of greater than about 2.3 and low pressure turbine 46may have a pressure ratio that is greater than about 5. In variousembodiments, the bypass ratio of gas turbine engine 20 is greater thanabout ten (10:1). In various embodiments, the diameter of fan 42 may besignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 may have a pressure ratio that is greaterthan about (5:1). Low pressure turbine 46 pressure ratio may be measuredprior to inlet of low pressure turbine 46 as related to the pressure atthe outlet of low pressure turbine 46 prior to an exhaust nozzle. Itshould be understood, however, that the above parameters are exemplaryof various embodiments of a suitable geared architecture engine and thatthe present disclosure contemplates other gas turbine engines includingdirect drive turbofans.

In various embodiments, with reference to FIG. 2A, a mid-turbine frame(MTF) assembly is illustrated. MTF assembly 257 may include bearingcompartment 238, outer case 266, and inner case 268. MTF vane 259 may belocated between inner case 268 and outer case 266. Oil tube fitting 212may be attached to a portion of bearing compartment 238. Oil tube 206may extend between outer case 266 and oil tube fitting 212. Oil 214 maybe located within oil tube 206. Oil 214 may be used to lubricate atleast a portion of bearing compartment 238. Oil tube 206 may be locatedat least partially within MTF vane 259. Sleeve 210 may encase at least aportion of oil tube 206. Oil tube fitting heat shield (also referred toherein as heat shield) 202 may be located between MTF vane 259 and oiltube fitting 212.

Extremely hot exhaust may impinge on MTF vane 259 which may cause MTFvane 259 to increase in temperature due to convective heat transfer fromthe hot exhaust. Heat waves 218 may radiate from MTF vane 259. Invarious embodiments, heat waves may radiate to other nearby componentswhich may cause the nearby components to increase in temperature. Inreturn, the nearby components may transfer heat conductively to otheradjacent components and/or fluids. For example, heat waves may radiatefrom MTF vane 259 to oil tube 206 which may convectively transfer heatfrom MTF vane 259 to oil tube 206. Heat may be conductively transferredto oil located inside oil tube 206. Furthermore, when oil exceedsvarious threshold temperatures, it may undergo severe oxidative andthermal breakdown which may cause solid deposits to form. These depositsmay be undesirable as they may impede the flow of fluid through variouscomponents including, for example, tubes and filters. Heat shield 202may be configured to block heat waves 218 radiating from MTF vane 259from directly impinging on oil tube fitting 212. Furthermore, heatshield 202 may help minimize convective heat transfer from hot airsurrounding oil tube fitting 212. Accordingly, heat shield 202 may helpblock heat from being transferred to oil tube fitting 212. In variousembodiments, heat shield 202 may help prevent oil from coking within oiltube fitting 212. Sleeve 210 may be configured to block radiating heatwaves from MTF vane 259 from impinging on oil tube 206.

In various embodiments, with reference to FIG. 2B, oil tube 206 maycomprise an inner tube 207 and an outer tube 208. Accordingly, oil tube206 may be referred to as a dual wall tube. Inner tube 207 may beenclosed by outer tube 208. There may be a space between inner tube 207and outer tube 208 which may be occupied by air. The outer tube 208 maybe configured to contain oil within outer tube 208 in the event thatthere is an oil leak from inner tube 207. Outer tube 208 may beconfigured to prevent heat transfer from surrounding hot air to innertube 207. Oil tube 206 may be configured to attach to oil tube fitting212. Oil tube 206 may be attached to oil tube fitting 212 via weld,solder, braze, or any other suitable method. Heat shield 202 maycomprise a base portion 204 and a top portion 203. Top portion 203 ofheat shield 202 may be configured to attach to oil tube 206. Top portion203 of heat shield 202 may be configured to attach to oil tube 206 viaweld, solder, braze, or any other suitable method. Top portion 203 ofheat shield 202 may be configured to attach to oil tube 206 in closeproximity to an end of oil tube 206. Top portion 203 of heat shield 202may be configured to attach to oil tube 206 in close proximity to aproximal end of oil tube 206. Top portion 203 of heat shield 202 may beconfigured to attach to oil tube 206 such that there is a small gapbetween heat shield 202 and sleeve 210. Base portion 204 of heat shield202 may be configured to at least partially encase oil tube fitting 212.

In various embodiments, various components of MTF assemblies maycomprise various materials. Various components, including heat shield202, may comprise a high temperature metal (e.g., an austeniticnickel-chromium-based alloy such as INCONEL), a high temperaturecomposite, and/or the like. In further embodiments, heat shield 202 maycomprise a high temperature stainless steel.

In various embodiments, heat shield 202 may comprise a wall thickness“T.” In various embodiments, heat shield 202 may be manufactured via ahydro-forming process. Wall thickness “T” may be chosen according tovarious design considerations. In various embodiments, wall thickness“T” may be between 0.010 in (0.25 mm) and 0.030 in (0.76 mm) in thick.During manufacturing, sheet metal of a preferred wall thickness may bechosen to be hydro-formed to the desired heat shield geometry. Forexample, if a heat shield comprising a wall thickness of 0.5 mm isdesired, a piece of sheet metal comprising a wall thickness of 0.5 mmmay be used and formed into the desired geometry using high pressurehydraulic fluid to press the sheet metal into a die in a process knownas hydro-forming. In various embodiments, a single piece of sheet metalmay be hydro-formed into heat shield 202. In various embodiments, two ormore pieces of sheet metal may be hydro-formed into different geometriesand welded together to form heat shield 202.

With reference to FIG. 3A and FIG. 3B, elements with like elementnumbering as depicted in FIG. 2A and FIG. 2B, are intended to be thesame and certain properties, including material properties, will not berepeated for the sake of clarity.

In various embodiments, with reference to FIG. 3A and FIG. 3B, oil tubefitting 312 may be separated from heat shield 302 by a gap “G”. Heatshield 302 may be configured to be separated from oil tube fitting 312by gap “G” such that a conductive thermal path does not exist betweenheat shield 302 and oil tube fitting 312. Gap “G” may be configured tobe minimal while allowing thermal expansion of heat shield 302 and oiltube fitting 312 without creating a thermal conduction path between heatshield 302 and oil tube fitting 312. Minimizing gap “G” may allow heatshield 302 to more effectively minimize convective heat transfer betweenoil tube fitting 312 and surrounding hot air. Minimizing gap “G” mayallow heat shield 302 to more effectively minimize convective heattransfer between oil tube fitting 312 and radiated heat from an adjacentMTF vane.

In various embodiments, the base portion 304 of heat shield 302 maycomprise a triangular geometry. For example, FIG. 3B illustrates thebase portion 304 of heat shield 302, wherein the base portion bounds atriangular void. In various embodiments, the base portion 304 of heatshield 302 may comprise one of a square, rectangular, oblong, round,elliptical, or any other geometry. The geometry of the base portion 304of heat shield 302 may be driven by the geometry of oil tube fitting312. Accordingly, the geometry of oil tube fitting 312 and base portion304 may be complementary. In various embodiments, the top portion 303 ofheat shield 302 may comprise an ovular geometry. For example, FIG. 3Billustrates the top portion 303 of heat shield 302, wherein the topportion 303 bounds an ovular void. In various embodiments, the topportion 303 of heat shield 302 may comprise a square, rectangular,oblong, round, elliptical, or any other geometry. The geometry of thetop portion 303 of heat shield 302 may be driven by the geometry of oiltube 306. Accordingly, the geometry of oil tube 306 and top portion 303may be complementary. In various embodiments, the geometry of topportion 303 and base portion 304 may be complementary. In variousembodiments, the geometry of top portion 303 and base portion 304 may bedifferent. In various embodiments, top portion 303 may be connected tobase portion 304 by a tapered portion 305.

In various embodiments, top portion 303 may comprise a cross-sectionalarea. The cross-sectional area of top portion 303 may be the area of aslice of top portion 303 taken along line B-B in the x-z plane accordingto the coordinates provided in FIG. 3A. The cross-sectional area of topportion 303 may be best visualized by viewing top portion 303 from thetop view as shown in FIG. 3B. In various embodiments, base portion 304may comprise a cross-sectional area. The cross-sectional area of baseportion 304 may be the area of a slice of base portion 304 taken alongline C-C in the x-z plane according to the coordinates provided in FIG.3A. The cross-sectional area of base portion 304 may be best visualizedby viewing base portion 304 from the top view as shown in FIG. 3B.

A method of cooling an oil tube fitting is disclosed herein, inaccordance with various embodiments. The method of cooling an oil tubefitting may include disposing a heat shield about an oil tube. When inthe installed position, the heat shield may at least partially encase anoil tube fitting. When in the installed position and during operation,the heat shield may be configured to prevent heat transfer between theoil tube fitting and surrounding hot air. When in the installedposition, the heat shield may be configured to be separated from the oiltube fitting by a gap.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is intended to invoke 35 U.S.C.112(f), unless the element is expressly recited using the phrase “meansfor.” As used herein, the terms “comprises”, “comprising”, or any othervariation thereof, are intended to cover a non-exclusive inclusion, suchthat a process, method, article, or apparatus that comprises a list ofelements does not include only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus.

What is claimed is:
 1. A heat shield comprising: a base portion, whereinthe base portion bounds a generally triangular-shaped void; a topportion, wherein the top portion bounds an ovular void; and a taperedportion, wherein the tapered portion extends between the base portionand the top portion, the top portion having a smaller cross-sectionalarea than the base portion.
 2. The heat shield of claim 1, wherein theheat shield is configured to at least partially encase a fitting.
 3. Theheat shield of claim 2, wherein the heat shield is configured to impedeheat transfer between the fitting and surrounding air.
 4. The heatshield of claim 3, wherein the heat shield and the fitting are separatedby a gap.
 5. The heat shield of claim 1, wherein the top portion isconfigured to be attached to a tube.
 6. The heat shield of claim 5,wherein the base portion is configured to receive a fitting attached tothe tube.
 7. The heat shield of claim 1, wherein the heat shield ismanufactured via a hydro-forming process.
 8. The heat shield of claim 1,wherein the heat shield comprises at least one of a nickel-chromiumbased alloy and a stainless steel.
 9. The heat shield of claim 1,wherein the base portion, the top portion, and the tapered portion areformed from a single piece of material.
 10. The heat shield of claim 1,wherein the heat shield is for a gas turbine engine.